Depending on how long its been sitting, I would definitely drain the tank and put fresh gas in. Today's gas doesn't last very long, any more than 3 or 4 months, it starts to go bad. New gas won't help on top of it either. The old gas will gum up the fuel lines, carb, fuel pump, etc. And with the small tank on the MB it shouldn't be too hard to drain it out the bottom, or if you have to, siphen it out the top.
Brakes are easy, most of the major venders can help you find the right wheel cylinders, etc to get it back on the road. And if it were mine, I would change all the major fluids, oil, antifreeze, etc. Good to start out new, and you will know its all good.
The folks on here are very knowledgable, so don't hesitate to ask as many questions as you want. A great group of people.
You definitely have a cool jeep, and these little critters are a lot of fun to drive around. We take our jeep to the local parades, into town to get icecream, etc...It turns a lot of heads, and my 1.5 year old son just loves the thing.
Good luck, and have fun!